觀無量壽佛經義疏 3.129

3.129

"‘The bodies of Bodhisattva Avalokiteśvara and Mahāsthāmaprāpta are everywhere identical to those of sentient beings; merely by contemplating the marks of their heads, one knows this is Avalokiteśvara and knows this is Mahāsthāmaprāpta.’" "Bodies identical to sentient beings" refers to the disciples of that realm; while the forms of the middle and lower grades are completely different, the great bodhisattvas could be mistaken for one another. The sūtra says: "The sentient beings who are born there are all avaivartikas; among them are many who will attain buddhahood in one more birth, their number being extremely large," and so forth. Merely by contemplating the marks on the head can one distinguish the two sages: Avalokiteśvara's crown has a standing Buddha, while Mahāsthāmaprāpta's uṣṇīṣa has a jeweled vase. Second, explaining their attendance to show the necessity of contemplation.